Outlet box knockout

Abstract

An electrical outlet box molded of plastic material has a knockout arrangement in a box wall that is formed by inner, intermediate and outer circular grooves that are eccentrically positioned to overlap at a tangent location and define inner, intermediate and outer eccentrically positioned circular knockouts. The grooves vary in depth from a minimum depth at the tangent location to a maximum depth opposite from the tangent location. Areas of increased weakness are provided in the box wall at the bottoms of at least the inner and intermediate grooves, and screwdriver slots are provided in the knockouts opposite from the tangent location.

Description

BACKGROUND OF THE INVENTION[0001]This application relates to electrical outlet boxes that are molded of plastic material and have knockouts molded into the box walls. However, it will be appreciated that the invention has broader aspects, and that the knockout arrangement of the present application can be used in other types of housings and enclosures.[0002]It is common to mold knockouts in the walls of electrical boxes to provide openings for attaching conduits and fittings to the box. It is difficult to mold the knockouts in a manner that provides easy removal of a desired knockout without dislodging other knockouts. It also is difficult to provide an arrangement for molding the knockouts into the box walls while ensuring plastic flow to the knockout areas during the molding process.SUMMARY OF THE INVENTION[0003]A knockout arrangement in a plastic wall includes inner, intermediate and outer circular grooves that are eccentric relative to one another and overlap at a tangent locati...

AI Technical Summary

Benefits of technology

"The invention is a knockout arrangement in a plastic wall that includes inner, intermediate, and outer circular grooves that are eccentric relative to each other and overlap at a tangent location. The grooves circumscribe inner, intermediate, and outer knockouts that have slots opposite from the tangent location for receiving the tip of a flat blade screwdriver to facilitate removal of the knockouts. The arrangement also includes weakened areas in the box wall at the bottom of the inner and intermediate grooves so that removal of the inner knockout will not result in removal of the intermediate or outer knockouts, and so that removal of both the inner and intermediate knockouts will not result in removal of the outer knockout. The minimum groove depth at the tangent location provides a path for flow of plastic across the grooves to fill the mold cavity in the area of all of the knockouts. The invention provides an improved knockout arrangement that provides easy knockout removal while minimizing the possibility that other knockouts will be undesirably displaced."

Problems solved by technology

It is difficult to mold the knockouts in a manner that provides easy removal of a desired knockout without dislodging other knockouts.

It also is difficult to provide an arrangement for molding the knockouts into the box walls while ensuring plastic flow to the knockout areas during the molding process.

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